1. Field of the Invention
The present invention relates to a composite material wing structure which is applied to, for example, the main wing of an airplane.
2. Description of the Related Art
There are many types of wing structures for airplanes as prior arts as shown in FIGS. 10 to 12 are known. The first example for the structure shown in FIG. 10 is the conventional wing structure made of such various parts as an upper skin 100, an lower skin 101, a front spar 102, a rear spar 103, and a plurality of ribs 104. And these members are permanently connected by various kinds of fasteners. Accordingly, this kind of the wing structure of the airplane has so many components that the assembly becomes very difficult for precisely mating each other because each has an allowable tolerance for manufacturing.
The second example shown in FIG. 11 is a little improved wing structure 115. According to the second type of the structure, first, a box spar is assembled with a front spar 112, a rear spar 113, and ribs 114. And next, the box spar is put on a lower skin 111, then forming a lower structure 115. Finally, an entire wing structure is made by covering the lower structure 115 with an upper skin 116. As a matter of fact, the lower structure 115 is integrally formed, however, it is still a simple concept of an integration of only the front and rear spars and the lower skin. The assembly still requires many jigs.
The third example of the conventional wing structure shown in FIG. 12 is a cross-sectional view where spars 118 are integrally formed on a lower skin 117, and then covered by an upper skin 119 thereon. After that, assembled are a leading edge 120 on the front side, and a trailing edge 121 on the rear side.
According to these conventional assembling methods, there are many drawbacks. That is, It means that the structure requires many assembling jigs not only for making each but also for sub-assembling and/or final assembly of all of them. It causes to become heavier and costlier.
Even though the spars and the ribs are integrally formed in the lower skin as shown in the third example, molding processes with many assembly jigs becomes very complicated and costlier due to many laborious works for laminating many layers of prepregs. Anyway, as either one of the skins must be fastened in the last process, the total cost of making this kind of wing structures becomes high.
It has been well known that a multi-spur integral molding system is less costlier for making the wing structure than the conventional ones shown in FIGS. 10 to 12, however, it is very difficult to make one integral wing structure because some components must receive a heavy load. For example, it is impossible to use such an integral structure for a structural member for bearing the heavy load applied from an aileron, a flap, a spoiler or a landing gear due to lacking the strength thereof.